1. Filed of the Invention
The present invention is related to a thermoplastic styrenic resin composition comprising a specific styrenic copolymer (A). It is further related to a rubber modified thermoplastic styrenic resin composition containing said styrenic copolymer (A) and rubber particle (B). The thermoplastic styrenic resin composition and the rubber modified thermoplastic styrenic resin composition have high fluidity and excellent processability such as vacuum forming.
2. Background of the Invention
It has been known that the thermoplastic styrenic resin are widely used in the manufacture of electric and electronic article as well as automobile parts because of characteristics on processing and mechanical properties, especially the better appearance and gloss.
Usually, the thermoplastic styrenic resin could be processed by such methods as injection, extrusion, blown molding, etc. As regards to the process such as vacuum forming, the styrenic resin should be extruded to form sheet in advance, and it is processed into the required shape by vacuum forming. For improving the vacuum formability, the resin should have high melt tension, namely having high molecular weight, to get better thickness uniformity and dimension stability in vacuum forming. The increased molecular weight will, however, normally decrease the fluidity, processability, and productivity, etc.
The improvement of both vacuum formability and fluidity could be achieved by adding branching agents, as given in Japanese patent publication such as 59-149912, 2-182711 and 8-269137. Generally, the branching agents added are polyfunctional vinyl monomers, such as divinyl compounds (for example divinyl benzene) or polyfunctional acrylic ester. In the case of these monomers applied in the process, the styrenic resin has well-balanced fluidity and processability (ex. Vacuum forming). But the cross linking will be easily occurred and the resin would be adhered to the wall of pipeline and generate contaminations. Furthermore, with the increase of continuous production time, the above-mentioned problems will become even more remarkable.
The object of the present invention is to provide a novel thermoplastic styrenic resin which is excellent in fluidity and vacuum formability along with excellent appearance of color on processing.
The present invention therefore provides a thermoplastic styrenic resin composition which comprises a styrenic copolymer (A) comprising 15-100 parts by weight of a unit derived from a styrenic monomer (i-1), 0-45 parts by weight of a unit derived from a vinyl cyanide monomer (i-2), 0-40 parts by weight of a unit derived from a copolymerizable vinyl monomer (i-3) other than above monomer, and 0.0005-1.0 parts by weight of a unit derived from a polyfunctional maleimide monomer, all based on 100 parts by weight of the total amount of (i-1) to (i-3)
The present invention further provides a rubber modified thermoplastic styrenic resin composition which comprises of a styrenic copolymer (A) as the continuous phase comprising 15-100 parts by weight of a unit derived from a styrenic monomer (i-1), 0-45 parts by weight of a unit derived from a vinyl cyanide monomer (i-2), 0-40 parts by weight of a unit derived from a copolymerizable vinyl monomer (i-3) other than the above monomers, and 0.0005-1.0 parts by weight of a unit derived from a polyfunctional maleimide monomer, all based on 100 parts by weight of the total amount of (i-1) to (i-3), and rubber particle (B) as the dispersed phase, wherein the rubber content of the rubber modified thermoplastic styrenic resin composition is in the range of 1-40 weight %.
The rubber modified thermoplastic styrenic resin composition thus obtained has excellent heat stability, impact strength, fluidity, thickness uniformity after vacuum forming process, and good uniformity of glass of the injection product after painting.